﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace XModem.library
{
  public interface CRC 
    {
         int   getCRCLength();
         long calcCRC(byte[] block);
         long calcCRC(byte[] buf, int index, int len);
        ///// <summary>
        ///// 计算 CRC
        ///// </summary>
        ///// <param name="paczka">计算表 CRC</param>
        ///// <returns>数组byte</returns>
        //public static byte[] Policz(byte[] paczka)
        //{
        //    byte[] ret = new byte[2];
        //    int count = paczka.Count();
        //    ushort sumaKontrolnaCRC = 0;
        //    int n = 0;
        //    while (--count >= 0)
        //    {
        //        sumaKontrolnaCRC = (ushort)(sumaKontrolnaCRC ^ paczka[n++] << 8);                                  // 拿个符号写八个零
        //        for (int j = 0; j < 8; ++j)
        //            if (Convert.ToBoolean(sumaKontrolnaCRC & 0x8000)) sumaKontrolnaCRC = (ushort)(sumaKontrolnaCRC << 1 ^ 0x1021); // 如果左位 bit == 1 运行异或生成器 1021
        //            else sumaKontrolnaCRC = (ushort)(sumaKontrolnaCRC << 1);                                   // 如果不是在0000前发生异或
        //    }
        //    sumaKontrolnaCRC = (ushort)(sumaKontrolnaCRC & 0xFFFF);
        //    return BitConverter.GetBytes(sumaKontrolnaCRC);
        //}

        //public static bool Sprawdz(byte[] paczka, byte[] CRC)
        //{
        //    ushort CRCtoCheck = BitConverter.ToUInt16(Policz(paczka), 0);
        //    ushort RealCRC = BitConverter.ToUInt16(CRC, 0);
        //    return !(Convert.ToBoolean(CRCtoCheck ^ RealCRC));
        //}



    }


    public class CRC8:CRC {
        public int getCRCLength()
        {
            return 1;
        }
        public long calcCRC(byte[] block)
        {
            byte checkSumma = 0;
            for (int i = 0; i < block.Count(); i++)
            {
                checkSumma += block[i];
            }
            return checkSumma;
        }

        public long calcCRC(byte[] buf, int index, int len)
        {
            throw new NotImplementedException();
        }
    }


    public class CRC16:CRC
    {
        public static ushort[] _crc16LookupTableold =
      {
              0x0000,0x1021,0x2042,0x3063,0x4084,0x50A5,0x60C6,0x70E7,
              0x8108,0x9129,0xA14A,0xB16B,0xC18C,0xD1AD,0xE1CE,0xF1EF,
              0x1231,0x0210,0x3273,0x2252,0x52B5,0x4294,0x72F7,0x62D6,
              0x9339,0x8318,0xB37B,0xA35A,0xD3BD,0xC39C,0xF3FF,0xE3DE,
              0x2462,0x3443,0x0420,0x1401,0x64E6,0x74C7,0x44A4,0x5485,
              0xA56A,0xB54B,0x8528,0x9509,0xE5EE,0xF5CF,0xC5AC,0xD58D,
              0x3653,0x2672,0x1611,0x0630,0x76D7,0x66F6,0x5695,0x46B4,
              0xB75B,0xA77A,0x9719,0x8738,0xF7DF,0xE7FE,0xD79D,0xC7BC,
              0x48C4,0x58E5,0x6886,0x78A7,0x0840,0x1861,0x2802,0x3823,
              0xC9CC,0xD9ED,0xE98E,0xF9AF,0x8948,0x9969,0xA90A,0xB92B,

              0x5AF5,0x4AD4,0x7AB7,0x6A96,0x1A71,0x0A50,0x3A33,0x2A12,
              0xDBFD,0xCBDC,0xFBBF,0xEB9E,0x9B79,0x8B58,0xBB3B,0xAB1A,
              0x6CA6,0x7C87,0x4CE4,0x5CC5,0x2C22,0x3C03,0x0C60,0x1C41,
              0xEDAE,0xFD8F,0xCDEC,0xDDCD,0xAD2A,0xBD0B,0x8D68,0x9D49,
              0x7E97,0x6EB6,0x5ED5,0x4EF4,0x3E13,0x2E32,0x1E51,0x0E70,
              0xFF9F,0xEFBE,0xDFDD,0xCFFC,0xBF1B,0xAF3A,0x9F59,0x8F78,
              0x9188,0x81A9,0xB1CA,0xA1EB,0xD10C,0xC12D,0xF14E,0xE16F,
              0x1080,0x00A1,0x30C2,0x20E3,0x5004,0x4025,0x7046,0x6067,
              0x83B9,0x9398,0xA3FB,0xB3DA,0xC33D,0xD31C,0xE37F,0xF35E,
              0x02B1,0x1290,0x22F3,0x32D2,0x4235,0x5214,0x6277,0x7256,

              0xB5EA,0xA5CB,0x95A8,0x8589,0xF56E,0xE54F,0xD52C,0xC50D,
              0x34E2,0x24C3,0x14A0,0x0481,0x7466,0x6447,0x5424,0x4405,
              0xA7DB,0xB7FA,0x8799,0x97B8,0xE75F,0xF77E,0xC71D,0xD73C,
              0x26D3,0x36F2,0x0691,0x16B0,0x6657,0x7676,0x4615,0x5634,
              0xD94C,0xC96D,0xF90E,0xE92F,0x99C8,0x89E9,0xB98A,0xA9AB,
              0x5844,0x4865,0x7806,0x6827,0x18C0,0x08E1,0x3882,0x28A3,
              0xCB7D,0xDB5C,0xEB3F,0xFB1E,0x8BF9,0x9BD8,0xABBB,0xBB9A,
              0x4A75,0x5A54,0x6A37,0x7A16,0x0AF1,0x1AD0,0x2AB3,0x3A92,
              0xFD2E,0xED0F,0xDD6C,0xCD4D,0xBDAA,0xAD8B,0x9DE8,0x8DC9,
              0x7C26,0x6C07,0x5C64,0x4C45,0x3CA2,0x2C83,0x1CE0,0x0CC1,

              0xEF1F,0xFF3E,0xCF5D,0xDF7C,0xAF9B,0xBFBA,0x8FD9,0x9FF8,
              0x6E17,0x7E36,0x4E55,0x5E74,0x2E93,0x3EB2,0x0ED1,0x1EF0
          };


        public static ushort[] _crc16LookupTable = {
               0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
               0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
               0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
               0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
               0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
               0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
               0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
               0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
               0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
               0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,

               0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
               0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
               0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
               0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
               0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
               0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
               0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
               0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
               0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
               0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,

               0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
               0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
               0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
               0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
               0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
               0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
               0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
               0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
               0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
               0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,

               0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
               0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78,
        };
        public int getCRCLength()
        {
            return 2;
        }

        public long calcCRC(byte[] buf, int index, int len)
        {
            int counter;
            ushort crc = 0;
            for (counter = 0; counter < len; counter++)
                crc = (ushort)((crc << 8) ^ _crc16LookupTable[((crc >> 8) ^ buf[index + counter]) & 0x00FF]);
            return crc;
        }

        public long calcCRC(byte[] block)
        {
            int crc = 0x0000;
            foreach (var item in block)
            {
                crc = ((crc << 8) ^ _crc16LookupTable[((crc >> 8) ^ (0xff & item))]) & 0xFFFF;
            }
            return crc;
        }
    }
}
